20 potassium ← calcium → scandium Mg ↑ Ca ↓ Sr Periodic Table - Extended Periodic Table
General
Name, Symbol, Number	calcium, Ca, 20
Chemical series	alkaline earth metals
Group, Period, Block	2, 4, s
Appearance	silvery white
Atomic mass	40.078(4) g/mol
Electron configuration	[Ar] 4s2
Electrons per shell	2, 8, 8, 2
Physical properties
Phase	solid
Density (near r.t.)	1.55 g·cm−3
Liquid density at m.p.	1.378 g·cm−3
Melting point	1115 K (842 °C, 1548 °F)
Boiling point	1757 K (1484 °C, 2703 °F)
Heat of fusion	8.54 kJ·mol−1
Heat of vaporization	154.7 kJ·mol−1
Heat capacity	(25 °C) 25.929 J·mol−1·K−1
Vapor pressure P/Pa 1 10 100 1 k 10 k 100 k at T/K 864 956 1071 1227 1443 1755
Atomic properties
Crystal structure	cubic face centered
Oxidation states	2 (strongly basic oxide)
Electronegativity	1.00 (Pauling scale)
Ionization energies (more)	1st: 589.8 kJ·mol−1
	2nd: 1145.4 kJ·mol−1
	3rd: 4912.4 kJ·mol−1
Atomic radius	180 pm
Atomic radius (calc.)	194 pm
Covalent radius	174 pm
Miscellaneous
Magnetic ordering	paramagnetic
Electrical resistivity	(20 °C) 33.6 nΩ·m
Thermal conductivity	(300 K) 201 W·m−1·K−1
Thermal expansion	(25 °C) 22.3 µm·m−1·K−1
Speed of sound (thin rod)	(20 °C) 3810 m/s
Young's modulus	20 GPa
Shear modulus	7.4 GPa
Bulk modulus	17 GPa
Poisson ratio	0.31
Mohs hardness	1.75
Brinell hardness	167 MPa
CAS registry number	7440-70-2
Selected isotopes
Main article: Isotopes of calcium iso NA half-life DM DE (MeV) DP 40Ca 96.941% Ca is stable with 20 neutrons 41Ca syn 1.03×105 y ε - 41K 42Ca 0.647% Ca is stable with 22 neutrons 43Ca 0.135% Ca is stable with 23 neutrons 44Ca 2.086% Ca is stable with 24 neutrons 45Ca syn 162.7 d β- 0.258 45Sc 46Ca 0.004% >2.8×1015 y β-β-  ? 46Ti 47Ca syn 4.536 d β- 0.694, 1.99 47Sc γ 1.297 - 48Ca 0.187% >4×1019 y β-β-  ? 48Ti
References

Calcium (IPA: /ˈkalsiəm/) is the chemical element in the periodic table that has the symbol Ca and atomic number 20. Calcium is a soft grey alkaline earth metal that is used as a reducing agent in the extraction of thorium, zirconium and uranium. Calcium is also the fifth most abundant element in the Earth's crust. It is essential for living organisms, particularly in cell physiology, and is the most common metal in many animals. General Name, Symbol, Number potassium, K, 19 Chemical series alkali metals Group, Period, Block 1, 4, s Appearance silvery white Atomic mass 39. ... General Name, Symbol, Number scandium, Sc, 21 Chemical series transition metals Group, Period, Block 3, 4, d Appearance silvery white Atomic mass 44. ... General Name, Symbol, Number magnesium, Mg, 12 Chemical series alkaline earth metals Group, Period, Block 2, 3, s Appearance silvery white Atomic mass 24. ... General Name, Symbol, Number strontium, Sr, 38 Chemical series alkaline earth metals Group, Period, Block 2, 5, s Appearance silvery white metallic Atomic mass 87. ... Calcium table image created for Wikipedia by Schnee on June 25, 2003, 9:51 UTC. Licensed under the terms of the GNU FDL. File links The following pages link to this file: Calcium User:Femto/elements e3 Categories: GFDL images ... This is a standard display of the periodic table of elements. ... This extended periodic table was suggested by Glenn T. Seaborg in 1969. ... This is a list of chemical elements, sorted by name and color coded according to type of element. ... Categories: Chemical elements ... sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex sex... The alkaline earth metals are the series of elements in Group 2 (IUPAC style) of the periodic table: beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) and radium (Ra) (not always considered due to its radioactivity and very short half-life). ... A periodic table group is a vertical column in the periodic table of the chemical elements. ... In the periodic table of the elements, a period is a row of the table. ... A block of the periodic table of elements is a set of adjacent groups. ... The alkaline earth metals are the series of elements in Group 2 of the periodic table: beryllium, magnesium, calcium, strontium, barium and radium (not always considered due to its very short half-life). ... A period 4 element is one of the chemical elements in the fourth row (or period) of the periodic table of the elements. ... The s-block of the periodic table of elements consists of the first two groups: the alkali metals and alkaline earth metals, plus hydrogen. ... Color is an important part of the visual arts. ... Calcium sample. ... The atomic mass of a chemical element is the mass of an atom at rest, most often expressed in unified atomic mass units. ... To help compare different orders of magnitude we list here masses between 6. ... Hydrogen = 1 List of Elements in Atomic Number Order. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... General Name, Symbol, Number argon, Ar, 18 Chemical series noble gases Group, Period, Block 18, 3, p Appearance colorless Atomic mass 39. ... Properties The electron is a lightweight fundamental subatomic particle that carries a negative electric charge. ... In atomic physics, an electron shell, also known as a main energy level, is a group of atomic orbitals with the same value of the principal quantum number n. ... In the physical sciences, a phase is a set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties (i. ... In jewelry, a solid gold piece is the alternative to gold-filled or gold-plated jewelry. ... Density (symbol: ρ - Greek: rho) is a measure of mass per volume. ... Room temperature, in laboratory reports, is taken to be roughly 21–23 degrees Celsius (69-73 degrees Fahrenheit), or 294–296 kelvins. ... Density (symbol: ρ - Greek: rho) is a measure of mass per volume. ... The melting point of a solid is the temperature at which it changes state from solid to liquid. ... The melting point of a solid is the temperature at which it changes state from solid to liquid. ... The kelvin (symbol: K) is the SI unit of temperature, and is one of the seven SI base units. ... The Celsius scale is a temperature scale named after the Swedish astronomer Anders Celsius (1701 â€“ 1744), who first proposed a similar system two years before his death. ... Fahrenheit is a temperature scale named after the German physicist Gabriel Fahrenheit (1686–1736), who proposed it in 1724. ... The boiling point of a substance is the temperature at which it can change its state from a liquid to a gas throughout the bulk of the liquid at a given pressure. ... The kelvin (symbol: K) is the SI unit of temperature, and is one of the seven SI base units. ... The Celsius scale is a temperature scale named after the Swedish astronomer Anders Celsius (1701 â€“ 1744), who first proposed a similar system two years before his death. ... Fahrenheit is a temperature scale named after the German physicist Gabriel Fahrenheit (1686–1736), who proposed it in 1724. ... The standard enthalpy change of fusion, also known as the heat of fusion, is the amount of thermal energy which must be absorbed or lost for 1 gram of a substance to change states from a solid to a liquid or vice versa. ... Kilojoule per mole are an SI derived unit of energy per amount of material, where energy is measured in units of 1000 joules, and the amount of material is measured in mole units. ... The standard enthalpy change of vaporization, ΔvHo, also (less correctly) known as the heat of vaporization is the energy required to transform a given quantity of a substance into a gas. ... Kilojoule per mole are an SI derived unit of energy per amount of material, where energy is measured in units of 1000 joules, and the amount of material is measured in mole units. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... In chemistry and physics, Vapor pressure is the pressure of a vapor in equilibrium with its non-vapor phases. ... Rose des Sables (Sand Rose), formed of gypsum crystals In mineralogy and crystallography, a crystal structure is a unique arrangement of atoms in a crystal. ... In chemical nomenclature, the oxidation number (formerly known as the Stock number) of an element in a molecule or complex is the charge that it would bear if all the ligands were removed along with the electron pairs that were shared with the central atom. ... A bases in chemistry is a chemical substance which has a free pair of electrons to bind a Hydrogen ion commonly referred to as a proton (IUPAC definition). ... Electronegativity is a measure of the ability of an atom or molecule to attract electrons in the context of a chemical bond. ... The ionization energy (IE) of an atom or of a molecule is the energy required to strip it of an electron. ... These tables list the ionization energy in kJ/mol necessary to remove an electron from a neutral atom (first energy), respectively from a singly, doubly, etc. ... Kilojoule per mole are an SI derived unit of energy per amount of material, where energy is measured in units of 1000 joules, and the amount of material is measured in mole units. ... The atomic radius is the distance from the atomic nucleus to the outmost stable electron orbital in an atom that is at equilibrium. ... You have big harry skanky balls ... Picometre (American spelling: picometer) is an SI measure of length that is equal to 10−12 of a metre. ... You have big harry skanky balls ... Covalent radius in chemistry corresponds to half of the distance between two identical atomic nuclei, bound by a covalent bond. ... You have big harry skanky balls ... In physics, magnetism is one of the phenomena by which materials exert an attractive or repulsive force on other materials. ... Simple Illustration of a paramagnetic probe made up from miniature magnets. ... // Headline text POOP!! Danny Hornsby (also known as Gnome) is a measure indicating how strongly a Gnome can opposes the flow of electric current. ... In physics, thermal conductivity, k, is the intensive property of a material that indicates its ability to conduct heat. ... During heat transfer, the energy that is stored in the intermolecular bonds between atoms changes. ... The speed of sound is a term used to describe the speed of sound waves passing through an elastic medium. ... Metre per second (U.S. spelling: meter per second) is an SI derived unit of both speed (scalar) and velocity (vector), defined by distance in metres divided by time in seconds. ... This article is about a physical property. ... In materials science, shear modulus S, sometimes referred to as the modulus of rigidity, is defined as the ratio of shear stress to the shear strain: S = shear stress/shear strain = (F/A)/Φ. Another commonly accepted symbol is G. Shear modulus is usually measured in ksi (kips per square... The bulk modulus K of a fluid or solid is the inverse of the compressibility: where p is pressure and V is volume. ... When a sample of material is stretched in one direction, it tends to get thinner in the other two directions. ... Mohs scale of mineral hardness characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material. ... The Brinell scale characterises the indentation hardness of materials through the scale of penetration of an indenter, loaded on a material test-piece. ... CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences, mixtures and alloys. ... Calcium (Ca) Standard atomic mass: 40. ... An isotope is any of several different forms of an element each having different atomic mass. ... Natural abundance refers to the prevalence of different isotopes of an element as found in nature. ... Half-Life For a quantity subject to exponential decay, the half-life is the time required for the quantity to fall to half of its initial value. ... In physics, the decay mode describes a particular way a particle decays. ... The decay energy is the energy released by a nuclear decay. ... An electronvolt (symbol: eV) is the amount of energy gained by a single unbound electron when it falls through an electrostatic potential difference of one volt. ... In nuclear physics, a decay product, also known as a daughter product, is a nuclide resulting from the radioactive decay of a parent or precursor nuclide. ... This article needs to be cleaned up to conform to a higher standard of quality. ... This article or section does not cite its references or sources. ... A Synthetic radioisotope is a radionuclide that is not found in nature: no natural process or mechanism exists which produces it, or it is so unstable that it decays away in a very short period of time. ... To help compare orders of magnitude of different times this page lists times between 32 000 years and 320 000 years (1012 seconds—a terasecond—and 1013 seconds). ... Electron capture is a decay mode for isotopes that will occur when there are too many protons in the nucleus of an atom, and there isnt enough energy to emit a positron; however, it continues to be a viable decay mode for radioactive isotopes that can decay by positron... General Name, Symbol, Number potassium, K, 19 Chemical series alkali metals Group, Period, Block 1, 4, s Appearance silvery white Atomic mass 39. ... This article needs to be cleaned up to conform to a higher standard of quality. ... This article or section does not cite its references or sources. ... This article needs to be cleaned up to conform to a higher standard of quality. ... This article or section does not cite its references or sources. ... This article needs to be cleaned up to conform to a higher standard of quality. ... This article or section does not cite its references or sources. ... A Synthetic radioisotope is a radionuclide that is not found in nature: no natural process or mechanism exists which produces it, or it is so unstable that it decays away in a very short period of time. ... To help compare orders of magnitude of different times this page lists times between 116 days and 1157 days or 3. ... In nuclear physics, beta decay (sometimes called neutron decay) is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted. ... General Name, Symbol, Number scandium, Sc, 21 Chemical series transition metals Group, Period, Block 3, 4, d Appearance silvery white Atomic mass 44. ... To help compare orders of magnitude of different times, this page lists times longer than 1019 seconds (317 billion years) See also times of other orders of magnitude. ... In the process of beta decay unstable nuclei decay by converting a neutron in the nucleus to a proton and emitting an electron and anti-neutrino. ... General Name, Symbol, Number titanium, Ti, 22 Chemical series transition metals Group, Period, Block 4, 4, d Appearance silvery metallic Atomic mass 47. ... A Synthetic radioisotope is a radionuclide that is not found in nature: no natural process or mechanism exists which produces it, or it is so unstable that it decays away in a very short period of time. ... To help compare orders of magnitude of different times this page lists times between 105 seconds and 106 seconds (27. ... In nuclear physics, beta decay (sometimes called neutron decay) is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted. ... General Name, Symbol, Number scandium, Sc, 21 Chemical series transition metals Group, Period, Block 3, 4, d Appearance silvery white Atomic mass 44. ... This article is about electromagnetic radiation. ... To help compare orders of magnitude of different times, this page lists times longer than 1019 seconds (317 billion years) See also times of other orders of magnitude. ... In the process of beta decay unstable nuclei decay by converting a neutron in the nucleus to a proton and emitting an electron and anti-neutrino. ... General Name, Symbol, Number titanium, Ti, 22 Chemical series transition metals Group, Period, Block 4, 4, d Appearance silvery metallic Atomic mass 47. ... Recommended values for many properties of the elements, together with various references, are collected on these data pages. ... The International Phonetic Alphabet (IPA) is a system of phonetic notation devised by linguists to accurately and uniquely represent each of the wide variety of sounds (phones or phonemes) used in spoken human language. ... The periodic table of the chemical elements A chemical element, often called simply an element, is a substance that cannot be decomposed or transformed into other chemical substances by ordinary chemical processes. ... The periodic table of the chemical elements is a tabular method of displaying the chemical elements, first devised in 1869 by the Russian chemist Dmitri Mendeleev. ... In chemistry and physics, the atomic number (Z) is the number of protons found in the nucleus of an atom. ... The alkaline earth metals are the series of elements in Group 2 (IUPAC style) of the periodic table: beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) and radium (Ra) (not always considered due to its radioactivity and very short half-life). ... Semi-accurate illustration of a redox reaction Redox reactions include all chemical processes in which atoms have their oxidation number (oxidation state) changed. ... General Name, Symbol, Number thorium, Th, 90 Chemical series Actinides Group, Period, Block n/a, 7, f Appearance silvery white Atomic mass 232. ... General Name, Symbol, Number zirconium, Zr, 40 Chemical series transition metals Group, Period, Block 4, 5, d Appearance silvery white Atomic mass 91. ... General Name, Symbol, Number uranium, U, 92 Chemical series actinides Group, Period, Block n/a, 7, f Appearance silvery gray metallic; corrodes to a spalling black oxide coat in air Atomic mass 238. ... Earth (IPA: , often referred to as the Earth, Terra, or Planet Earth) is the third planet in the solar system in terms of distance from the Sun, and the fifth largest. ... A crab is an example of an organism. ... Cells in culture, stained for keratin (red) and DNA (green). ... Physiology (in Greek physis = nature and logos = word) is the study of the mechanical, physical, and biochemical functions of living organisms. ... Hot metal work from a blacksmith In chemistry, a metal (Greek: Metallon) is an element that readily forms positive ions (cations) and has metallic bonds. ... Phyla Subregnum Parazoa Porifera (sponges) Subregnum Agnotozoa Placozoa (trichoplax) Orthonectida (orthonectids) Rhombozoa (dicyemids) Subregnum Eumetazoa Radiata (unranked) (radial symmetry) Ctenophora (comb jellies) Cnidaria (coral, jellyfish, anemones) Bilateria (unranked) (bilateral symmetry) Acoelomorpha (basal) Myxozoa (slime animals) Superphylum Deuterostomia (blastopore becomes anus) Chordata (vertebrates, etc. ...

Notable characteristics

Calcium is a rather soft, gray, metallic element that can be extracted by electrolysis from calcium fluoride. It burns with a yellow-red flame and forms a white nitride coating when exposed to air. It reacts with water, displacing hydrogen and forming calcium hydroxide. It has been suggested that Electrolytic process be merged into this article or section. ... Calcium fluoride (CaF2) is an insoluble ionic compound of calcium and fluorine. ... Definition The nitride ion is very very gay and retarded A nitride (compound) is a compound that has nitrogen with more electropositive elements. ... Calcium hydroxide is a chemical compound with the chemical formula Ca(OH)2. ...

Calcium is essential in muscle contraction, oocyte activation, building strong bones and teeth, blood clotting, nerve impulse transmission, regulating heartbeat, and fluid balance within cells. In the U.S., between about 50% and 75% of adults do not get sufficient calcium in their diet.^[1] Adults need between 1,000 and 1,300 mg of calcium in their daily diet.^[1] Motto: (traditional) In God We Trust (official, 1956–present) Anthem: The Star-Spangled Banner Capital Washington, D.C. Largest city New York City Official language(s) None at the federal level; English de facto Government Federal Republic  - President George W. Bush (R)  - Vice President Dick Cheney (R) Independence - Declared - Recognized...

The most abundant isotope, ⁴⁰Ca, has a nucleus of 20 protons and 20 neutrons. Its electron configuration is: 2 electrons in the K shell (principal quantum number 1), 8 in the L shell (principal quantum number 2), 8 in the M shell (principal quantum number 3), and 2 in the N shell (principal quantum number 4). The outer shell is the valence shell, with 2 electrons in the lone 4s orbital, the 3d orbitals being empty. The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ...

Occurrence

Calcium is not naturally found in its elemental state. Calcium is found mostly in soil systems as limestone, gypsum and fluorite. Stalagmites and stalactites contain calcium carbonate. Being an essential macromineral in the human diet, soil conservation practices often consider the sustainable equilibrium of calcium concentrations in the earth. Limey shale overlaid by limestone. ... Gypsum is a very soft mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O. // [edit] Chemical structure Heating gypsum to between 100°C and 150°C (302°F) partially dehydrates the mineral by driving off exactly 75% of the water contained in its chemical structure. ... Fluorite (also called fluor-spar) is a mineral composed of calcium fluoride, CaF2. ... The Witchs Finger in the Carlsbad Caverns A stalagmite (Greek stalagma, drip) is a type of speleothem formed by the deposit of calcium carbonate which rises from the floor of a limestone cave due to the dripping of mineralized solutions. ... A stalactice hanging above subterranean water. ... Calcium carbonate is a chemical compound, with chemical formula CaCO3. ... Macrominerals (also known as macroelements or bulk minerals) are macronutrients that are chemical elements. ... Sheep pasture with macroscale erosion, Australia Soil conservation is a set of management strategies for prevention of soil being eroded from the earth’s surface or becoming chemically altered by overuse, salinization, acidification, or other chemical soil contamination. ...

See also Calcium minerals.

Applications

Uses include:

• as a reducing agent in the extraction of other metals, such as uranium, zirconium, and thorium.
• as a deoxidizer, desulfurizer, or decarbonizer for various ferrous and nonferrous alloys.
• as an alloying agent used in the production of aluminium, beryllium, copper, lead, and magnesium alloys.
• in the making of cements and mortars to be used in construction.

A reducing agent is the element or a compound in a redox (reduction-oxidation) reaction (see electrochemistry) that reduces another species. ... General Name, Symbol, Number uranium, U, 92 Chemical series actinides Group, Period, Block n/a, 7, f Appearance silvery gray metallic; corrodes to a spalling black oxide coat in air Atomic mass 238. ... General Name, Symbol, Number zirconium, Zr, 40 Chemical series transition metals Group, Period, Block 4, 5, d Appearance silvery white Atomic mass 91. ... General Name, Symbol, Number thorium, Th, 90 Chemical series Actinides Group, Period, Block n/a, 7, f Appearance silvery white Atomic mass 232. ... General Name, Symbol, Number iron, Fe, 26 Chemical series transition metals Group, Period, Block 8, 4, d Appearance lustrous metallic with a grayish tinge Atomic mass 55. ... An alloy is a combination, either in solution or compound, of two or more elements, at least one of which is a metal, and where the resulting material has metallic properties. ... General Name, Symbol, Number aluminium, Al, 13 Chemical series poor metals Group, Period, Block 13, 3, p Appearance silvery Atomic mass 26. ... General Name, Symbol, Number beryllium, Be, 4 Chemical series alkaline earth metals Group, Period, Block 2, 2, s Appearance white-gray metallic Atomic mass 9. ... General Name, Symbol, Number copper, Cu, 29 Chemical series transition metals Group, Period, Block 11, 4, d Appearance metallic pinkish red Atomic mass 63. ... General Name, Symbol, Number lead, Pb, 82 Chemical series poor metals Group, Period, Block 14, 6, p Appearance bluish white Atomic mass 207. ... General Name, Symbol, Number magnesium, Mg, 12 Chemical series alkaline earth metals Group, Period, Block 2, 3, s Appearance silvery white Atomic mass 24. ... In the most general sense of the word, cement is a binder, a substance which sets and hardens independently, and can bind other materials together. ... Mortar holding bricks. ... Cranes are essential in large construction projects, such as this skyscraper In project architecture and civil engineering, construction is the building or assembly of any infrastructure. ...

History

Calcium (Latin calcis, meaning "lime") was known as early as the first century when the Ancient Romans prepared lime as calcium oxide. It was not actually isolated until 1808 in England when Sir Humphrey Davy electrolyzed a mixture of lime and mercuric oxide. Davy was trying to isolate calcium and when he heard that Berzelius and Pontin prepared calcium amalgam by electrolyzing lime in mercury, he tried it himself. He worked with electrolysis throughout his life and also discovered/isolated magnesium, strontium and barium. Latin is an ancient Indo-European language originally spoken in Latium, the region immediately surrounding Rome. ... The Roman Forum was the central area around which ancient Rome developed. ... Calcium oxide (CaO), commonly known as lime, quicklime or burnt lime, is a widely used chemical compound. ... Motto: (French for God and my right) Anthem: Multiple unofficial anthems Capital London Largest city London Official language(s) English (de facto) Government Constitutional monarchy  - Queen Queen Elizabeth II  - Prime Minister Tony Blair MP Unification    - by Athelstan AD 927  Area    - Total 130,395 km² (1st in UK)   50,346 sq... Please wikify (format) this article or section as suggested in the Guide to layout and the Manual of Style. ... It has been suggested that Electrolytic process be merged into this article or section. ... General Name, Symbol, Number magnesium, Mg, 12 Chemical series alkaline earth metals Group, Period, Block 2, 3, s Appearance silvery white Atomic mass 24. ... General Name, Symbol, Number strontium, Sr, 38 Chemical series alkaline earth metals Group, Period, Block 2, 5, s Appearance silvery white metallic Atomic mass 87. ... General Name, Symbol, Number barium, Ba, 56 Chemical series alkaline earth metals Group, Period, Block 2, 6, s Appearance silvery white Atomic mass 137. ...

Compounds

Calcium, combined with phosphate to form hydroxylapatite, is the mineral portion of human and animal bones and teeth. The mineral portion of some corals can also be transformed into hydroxylapatite. Above is a ball-and-stick model of the inorganic phosphate molecule (HPO42−). Colour coding: P (orange); O (red); H (white). ... Hydroxylapatite is a naturally occurring form of calcium apatite with the formula Ca5(PO4)3(OH), but is usually written Ca10(PO4)6(OH)2 to denote that the crystal unit cell comprises two molecules. ... Subclasses Alcyonaria Zoantharia See text for orders. ...

Calcium oxide (lime) is used in many chemical refinery processes and is made by heating and carefully adding water to limestone. When lime is mixed with sand, it hardens into a mortar and is turned into plaster by carbon dioxide uptake. Mixed with other compounds, lime forms an important part of Portland cement. Calcium oxide (CaO), commonly known as lime, quicklime or burnt lime, is a widely used chemical compound. ... Limey shale overlaid by limestone. ... Mortar holding bricks. ... // Gypsum plaster Plaster of Paris, or simply plaster, is a type of building material based on calcium sulfate hemihydrate, nominally (CaSO₄)₂*H₂O. It is created by heating gypsum to about 150 ℃, 2(CaSO₄ · 2H₂O) → (CaSO₄)₂ · H₂O + 3 H₂O (released as steam). ... Carbon dioxide is a chemical compound composed of one carbon and two oxygen atoms. ... Sampling fast set Portland cement Portland cement is the most common type of cement in general usage, as it is a basic ingredient of concrete, mortar and plaster. ...

When water percolates through limestone or other soluble carbonate rocks, it partially dissolves part of the rock and causes cave formation and characteristic stalactites and stalagmites and also forms hard water. Other important calcium compounds are nitrate, sulfide, chloride, carbide, cyanamide, and hypochlorite. Limey shale overlaid by limestone. ... In inorganic chemistry, a carbonate is a salt of carbonic acid. ... Water droplet coming out of the central canal of a stalactite A stalactite (Greek stalaktos, dripping Σταλακτίτης), or dripstone, is a type of speleothem that hangs from the ceiling or wall of limestone caves. ... The Witchs Finger in the Carlsbad Caverns A stalagmite (from the Greek stalagma, drop) is a type of speleothem that rises from the floor of a limestone cave due to the dripping of mineralized solutions and the depositation of calcium carbonate. ... Hard water is water that has a high mineral content (water with a low mineral content is known as soft water). ... Calcium nitrate, also called Norgessalpeter (Norwegian saltpeter) and Kalksalpeter, is a soluble salt with the formula Ca(NO3)2. ... Calcium sulfide (CaS), also known as calcium monosulfide, hepar calcies, and sulfurated lime, is a white cubic crystal used in the manufacturing of phosphors, and as an insecticide and fungicide. ... Calcium chloride is a chemical compound of calcium and chlorine. ... Calcium carbide is a chemical compound with the chemical formula CaC2. ... CaCN2 Calcium compound. ... It has been suggested that this article or section be merged with Calcium oxy chloride. ...

Isotopes

Calcium has four stable isotopes (⁴⁰Ca and ⁴²Ca through ⁴⁴Ca), plus two more isotopes (⁴⁶Ca and ⁴⁸Ca) that have such long half-lives that for all practical purposes they can be considered stable. It also has a cosmogenic isotope, radioactive ⁴¹Ca, which has a half-life of 103,000 years. Unlike cosmogenic isotopes that are produced in the atmosphere, ⁴¹Ca is produced by neutron activation of ⁴⁰Ca. Most of its production is in the upper metre or so of the soil column where the cosmogenic neutron flux is still sufficiently strong. ⁴¹Ca has received much attention in stellar studies because it decays to ⁴¹K, a critical indicator of solar-system anomalies. An isotope is any of several different forms of an element each having different atomic mass. ... Calcium 48 is a rare isotope of calcium. ... Cosmogenic isotopes are rare radioactive isotopes created when cosmic radiation interacts with an atomic nucleus. ... Radioactive decay is the set of various processes by which unstable atomic nuclei (nuclides) emit subatomic particles. ... Half-Life For a quantity subject to exponential decay, the half-life is the time required for the quantity to fall to half of its initial value. ... Cosmogenic isotopes are rare radioactive isotopes created when cosmic radiation interacts with an atomic nucleus. ... Layers of Atmosphere (NOAA) Air redirects here. ... This article or section does not cite its references or sources. ...

97% of naturally occurring calcium is in the form of ⁴⁰Ca. ⁴⁰Ca is one of the daughter products of ⁴⁰K decay, along with ⁴⁰Ar. While K-Ar dating has been used extensively in the geological sciences, the prevalence of ⁴⁰Ca in nature has impeded its use in dating. Techniques using mass spectrometry and a double spike isotope dilution have been used for K-Ca age dating. Potassium-argon or K-Ar dating is a method used by archaeologists and geologists to ascertain the date of ancient mineral deposits. ... The Blue Marble: The famous photo of the Earth taken en route to the Moon by Apollo 17s Harrison Schmitt on December 7, 1972. ... Basic schematic of a mass spectrometer Mass spectrometry (also know as mass spectroscopy (incorrect)[1] or in common speech mass-spec) is an analytical technique used to measure the mass-to-charge ratio of ions. ... General Name, Symbol, Number potassium, K, 19 Chemical series alkali metals Group, Period, Block 1, 4, s Appearance silvery white Atomic mass 39. ...

Nutrition

Calcium is an important component of a healthy diet. A deficit can affect bone and tooth formation, while overretention can cause kidney stones. Vitamin D is needed to absorb calcium. Dairy products, such as milk and cheese, are a well-known source of calcium. However, some individuals are allergic to dairy products and even more people, particularly those of non-European descent, are lactose-intolerant, leaving them unable to consume dairy products. Fortunately, many other good sources of calcium exist. These include: seaweeds such as kelp, wakame and hijiki; nuts and seeds (like almonds and sesame); beans; amaranth; collard greens; okra; rutabaga; broccoli; kale; and fortified products such as orange juice and soy milk. Calcium has also been found to assist in the production of lymphatic fluids. It has been suggested that Healthy eating be merged into this article or section. ... Kidney stones are solid accretions (crystals) of dissolved minerals in urine found inside the kidneys or ureters. ... Vitamin D is a fat soluble vitamin that contributes to the maintenance of normal levels of calcium and phosphorus in the bloodstream. ... Dairy products are generally defined as foodstuffs produced from milk. ... Lactose intolerance is the name given to the condition (found in the majority of humans) in which lactase, an enzyme needed for proper metabolization of lactose, is not produced in adulthood. ... Families Alariaceae Chordaceae Laminariaceae Lessoniaceae Phyllariaceae Pseudochordaceae Kelp are large seaweeds, belonging to the brown algae and classified in the order Laminariales. ... Binomial name Undaria pinnatifida (Harvey) Suringar, 1873 Wakame (Japanese: わかめ or 若布) is a type of edible kelp. ... Hijiki or hiziki (Japanese: 鹿尾菜 or 羊栖菜) (Sargassaceae), is a type of edible seaweed commonly found on rocky coastlines. ... Binomial name Prunus dulcis (Mill. ... Binomial name Sesamum indicum L. Sesame (Sesamum indicum) is a flowering plant in the genus Sesamum. ... This article is on the plant. ... Species See text. ... Cultivar Group Brassica oleracea Acephala Group Collard or collard greens is a loose-leafed cultivar group of Brassica oleracea Acephala Group, which is grown as a food crop and garden ornamental, mainly in Brazil, United States. ... Binomial name Abelmoschus esculentus (L.) Moench Okra, or ladys finger is a flowering plant in the mallow family Malvaceae, originating somewhere near present-day Ethiopia. ... Binomial name Brassica napobrassica The rutabaga or swede or (yellow) turnip (Brassica napobrassica, or Brassica napus var. ... Broccoli is a plant of the Cabbage family, Brassicaceae (formerly Cruciferae). ... Curly kale Kale is a form of cabbage (Brassica oleracea Acephala Group) in which the central leaves do not form a head. ... A can of Yeos soy milk, poured into a glass Soy milk (also called soymilk, soya milk, soybean milk, soy bean milk, soy drink, or soy beverage) is a milk-like beverage made from soybeans. ...

Calcium is essential for the normal growth and maintenance of bones and teeth, and calcium requirements must be met throughout life. Requirements are greatest during periods of growth, such as childhood, during pregnancy and when breast-feeding. Long-term calcium deficiency can lead to osteoporosis, in which the bone deteriorates and there is an increased risk of fractures. Adults need between 1,000 and 1,300 mg of calcium in their daily diet.^[1] Osteoporosis is a disease of bone in which bone mineral density (BMD) is reduced, bone microarchitecture is disrupted, and the amount and variety of non-collagenous proteins in bone is changed. ...

Recommended Adequate Intake by the IOM for Calcium:^[1]

Age------------------------Calcium (mg/day)

0 to 6 months--------------210

7 to 12 months-------------270

1 to 3 years---------------500

4 to 8 years---------------800

9 to 13 years-------------1300

14 to 18 years------------1300

19 to 50 years------------1000

51+ years-----------------1200

For more information about calcium in living nature, see calcium in biology and calcium metabolism. Calcium plays a vital role in the anatomy, physiology and biochemistry of organisms and of the cell, particularly in signal transduction pathways. ... Calcium metabolism or calcium homeostasis is the mechanism by which the body maintains adequate calcium levels. ...

Dietary sources of calcium

Calcium is found in significant amounts in many foods, including broccoli, kale, dandelion greens, collard greens, almonds, sesame seeds, blackstrap molasses, beans, and fortified beverages such as soy milk and orange juice. The calcium content of most foods can be found in the USDA National Nutrient Database.^[2] Broccoli is a plant of the Cabbage family, Brassicaceae (formerly Cruciferae). ... Curly kale Kale is a form of cabbage (Brassica oleracea Acephala Group) in which the central leaves do not form a head. ... Species See text. ... Cultivar Group Brassica oleracea Acephala Group Collard or collard greens is a loose-leafed cultivar group of Brassica oleracea Acephala Group, which is grown as a food crop and garden ornamental, mainly in Brazil, United States. ... This article refers to the plant. ... Binomial name Sesamum indicum L. Sesame (Sesamum indicum) is a flowering plant in the genus Sesamum. ... Molasses or treacle is a thick syrup by-product from the processing of the sugarcane or sugar beet into sugar. ... This article is on the plant. ... A can of Yeos soy milk, poured into a glass Soy milk (also called soymilk, soya milk, soybean milk, soy bean milk, soy drink, or soy beverage) is a milk-like beverage made from soybeans. ... Orange Juice was a Scottish post punk band founded in the middle class Glasgow suburb of Bearsden as the Nu-Sonics in 1976, becoming Orange Juice in 1979. ...

Dairy products (such as milk, yogurt and cheese) do contain calcium, however they are not recommended as a dietary source because they contain a significant amount of saturated fat, which can contribute to cardiovascular disease. The calcium content of dairy products is also misleading because most of the calcium is used by the body in the digestion of milk protein (casein). This can lead to calcium deficiency and osteoporosis. It has been suggested that this article or section be merged with Coronary heart disease. ... Please wikify (format) this article as suggested in the Guide to layout and the Manual of Style. ... Casein is the predominant phosphoprotein found in fresh milk and also in cheese. ... Osteoporosis is a disease of bone in which bone mineral density (BMD) is reduced, bone microarchitecture is disrupted, and the amount and variety of non-collagenous proteins in bone is changed. ...

However, calcium in dairy products is usually much more absorbable to human body than other sources of calcium such as plant based or dietary supplements.

Dietary calcium supplements

Calcium supplement are used to prevent and to treat calcium deficiencies. There are conflicting recommendations about when to take calcium supplements. However, most experts agree that no more than 500 mg should be taken at a time because the percent of calcium absorbed decreases as the amount of calcium in the supplement increases. ^[1] It is recommended to spread doses throughout the day, with the last dose near bedtime. Recommended daily calcium intake varies from 1000 to 1500 milligrams, depending upon the stage of life.

In July 2006, a report citing research from Fred Hutchinson Cancer Research Center in Seattle, Washington claimed that women in their 50's gained 5 pounds less in a period of 10 years by taking more than 500mg of calcium supplements than those who did not. However, the doctor in charge of the study, Dr. Alejandro J. Gonzalez also noted it would be stretching it to suggest calcium supplements as a weight-limiting aid..^[3]

• Calcium carbonate is the most common and least expensive calcium supplement. It can be difficult to digest and causes gas in some people. Taking magnesium with it can help to prevent constipation. Calcium carbonate is 40% elemental calcium. 1000 mg will provide 400 mg of calcium. Take this supplement with food to aid in absorption. In some calcium supplements based on calcium carbonate, Vitamin D is used as an addition to aid in absorption. Vitamin D is needed for the absorption of calcium from the stomach and for the functioning of calcium in the body. ^{[4] [5]}
• Calcium citrate is more easily absorbed (bioavailability is 2.5 times higher than calcium carbonate), easier to digest and less likely to cause constipation and gas than calcium carbonate. It also has a lower risk of contributing to the formation of kidney stones. Calcium citrate is 21% elemental calcium. 1000 mg will provide 210 mg of calcium. It is more expensive than calcium carbonate and more of it must be taken to get the same amount of calcium.
• Calcium phosphate costs more than calcium carbonate, but less than calcium citrate. It is easily absorbed and is less likely to cause constipation and gas than either.
• Calcium lactate and calcium aspartate are both more easily digested, but more expensive than calcium carbonate

See also

• Calcium compounds
• Disorders of calcium metabolism

Disorders of calcium metabolism occur when the body has too little or too much calcium. ...

Notes

1. ^ ^{a b c d e} Dietary Supplement Fact Sheet: Calcium. Retrieved on 2006-03-23.
2. ^ USDA National Nutrient Database
3. ^ Calcium may help women keep weight in check. Retrieved on 2006-09-25.
4. ^ drugs.com article about Calcium with Vitamin D. Retrieved on 2006-08-23.
5. ^ Caltro. Retrieved on 2006-08-23.

2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... March 23 is the 82nd day of the year in the Gregorian Calendar (83rd in Leap years). ... 2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... September 25 is the 268th day of the year (269th in leap years) in the Gregorian calendar. ... 2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... August 23 is the 235th day of the year in the Gregorian Calendar (236th in leap years), with 130 days remaining. ... 2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ... August 23 is the 235th day of the year in the Gregorian Calendar (236th in leap years), with 130 days remaining. ...

References

• Rebecca J. Donatelle. Health, The Basics. 6th ed. San Francisco: Pearson Education, Inc. 2005.

External links

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Calcium

Look up calcium in
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• WebElements.com – Calcium
• USDA National Nutrient Database, Calcium content of selected foods